An antifuse according to an embodiment of the invention herein can include a depletion mode metal oxide semiconductor field effect transistor (“MOSFET”) having a conduction channel and a metal gate overlying the conduction channel. A cathode and an anode of the antifuse can be electrically coupled to the gate, such that the antifuse is programmable by driving a programming current between the cathode and the anode to cause material of the metal gate to migrate away. Under appropriate biasing conditions, when the antifuse is unprogrammed, the conduction channel is turned on unless a voltage above a first threshold voltage is applied to the gate to turn off the conduction channel. The gate can be configured such that when the antifuse has been programmed, the conduction channel remains turned on even if a voltage above the first threshold voltage is applied between the gate and a source region of the MOSFET.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method of programming an antifuse, comprising: driving a programming current between a cathode and an anode of the antifuse, so as to drive the programming current through a gate of a depletion mode metal oxide semiconductor field effect transistor (“MOSFET”), the gate having at least one metal layer, in which the cathode and the anode are each electrically coupled to the gate and spaced apart from one another in a direction the gate extends, so as to create a gap in the metal layer.
2. The method as claimed in claim 1 , further comprising detecting whether the antifuse has been programmed by applying a voltage greater than a threshold voltage between the gate and a source region of the MOSFET and detecting whether the conduction channel turns off with such applied voltage.
3. The method as claimed in claim 1 , wherein the driving of the programming current generates a gap in the gate such that the conduction channel no longer turns off when the voltage greater than the threshold voltage is applied to the gate.
4. The method as claimed in claim 1 , wherein the MOSFET has a conduction channel, a source region, and a drain region separated from the source region by the conduction channel, wherein a resistance between a source region and the drain region has a first value when the antifuse is unprogrammed and the voltage greater than the threshold voltage is applied to the gate, and the resistance between the source region and the drain region has a second value when the antifuse has been programmed and the voltage greater than the threshold voltage is applied to the gate, the second value being one or more orders of magnitude lower than the first value.
5. The method as claimed in claim 1 , wherein the MOSFET includes a source region and a drain region separated from the source region by a conduction channel, the method further comprising detecting an electrical resistance between the source region and the drain region when a voltage greater than a threshold voltage for turning off the conduction channel is applied to the gate, and using the detected resistance to determine whether or not the antifuse has been programmed.
6. The method as claimed in claim 1 , wherein the step of driving the programming current is performed by applying a programming voltage which is the same as a power supply voltage used to operate field effect transistors on a semiconductor chip which embodies the antifuse.
7. The method as claimed in claim 1 , wherein the depletion mode MOSFET is a p-type channel depletion mode MOSFET, the method further comprising detecting whether the antifuse has been programmed while applying a voltage that is greater than ground to the gate.
8. The method as claimed in claim 1 , wherein the depletion mode MOSFET is an n-type channel depletion mode MOSFET, the method further comprising detecting whether the antifuse has been programmed while applying a voltage that is greater than gate to the ground.
9. A method of programming an antifuse comprising: driving a programming current between a cathode and an anode of the antifuse and through a gate of a depletion mode MOSFET, the gate overlying a conduction channel and having at least one metal layer, in which the cathode and the anode are each electrically coupled to the gate and spaced apart from one another in a direction the gate extends, so as to create a gap in the metal layer, wherein under appropriate biasing conditions, the gate is configured such that when the antifuse is unprogrammed, the conduction channel is turned on unless a voltage above a first threshold voltage is applied to the gate to turn off the conduction channel, and the gate being configured such that when the antifuse has been programmed, the conduction channel remains turned on even if a voltage above the first threshold voltage is applied between the gate and a source region of the MOSFET.
10. The method as claimed in claim 9 , further comprising detecting whether the antifuse has been programmed by applying a voltage greater than a threshold voltage between the gate and a source region of the MOSFET and detecting whether the conduction channel turns off with such applied voltage.
11. The method as claimed in claim 9 , wherein the driving of the programming current generates a gap in the gate such that the conduction channel no longer turns off when the voltage greater than the threshold voltage is applied to the gate.
12. The method as claimed in claim 9 , wherein the MOSFET has a conduction channel, a source region, and a drain region separated from the source region by the conduction channel, wherein a resistance between a source region and the drain region has a first value when the antifuse is unprogrammed and the voltage greater than the threshold voltage is applied to the gate, and the resistance between the source region and the drain region has a second value when the antifuse has been programmed and the voltage greater than the threshold voltage is applied to the gate, the second value being one or more orders of magnitude lower than the first value.
13. The method as claimed in claim 9 , wherein the MOSFET includes a source region and a drain region separated from the source region by a conduction channel, the method further comprising detecting an electrical resistance between the source region and the drain region when a voltage greater than a threshold voltage for turning off the conduction channel is applied to the gate, and using the detected resistance to determine whether or not the antifuse has been programmed.
14. The method as claimed in claim 9 , wherein the step of driving the programming current is performed by applying a programming voltage which is the same as a power supply voltage used to operate field effect transistors on a semiconductor chip which embodies the antifuse.
15. A method of programming an antifuse comprising: driving a programming current between a cathode and an anode of the antifuse and through a gate of a depletion mode MOSFET, the gate overlying a conduction channel and having at least one metal layer, in which the cathode and the anode are each electrically coupled to the gate and spaced apart from one another in a direction the gate extends, so as to create a gap in the metal layer, wherein under appropriate biasing conditions, the gate is configured such that when the antifuse is unprogrammed, the conduction channel is turned on unless a voltage above a first threshold voltage is applied to the gate to turn off the conduction channel, and the gate being configured such that when the antifuse has been programmed, the conduction channel remains turned on even if a voltage above the first threshold voltage is applied between the gate and a source region of the MOSFET, and wherein the gate is configured to conduct the programming current when a programming voltage of less than one volt is applied between the cathode and the anode which is the same as a power supply voltage that can be used to operate field effect transistors on a semiconductor chip which embodies the antifuse.
16. The method as claimed in claim 15 , further comprising detecting whether the antifuse has been programmed by applying a voltage greater than a threshold voltage between the gate and a source region of the MOSFET and detecting whether the conduction channel turns off with such applied voltage.
17. The method as claimed in claim 15 , wherein the driving of the programming current generates a gap in the gate such that the conduction channel no longer turns off when the voltage greater than the threshold voltage is applied to the gate.
18. The method as claimed in claim 15 , wherein the MOSFET has a conduction channel, a source region, and a drain region separated from the source region by the conduction channel, wherein a resistance between a source region and the drain region has a first value when the antifuse is unprogrammed and the voltage greater than the threshold voltage is applied to the gate, and the resistance between the source region and the drain region has a second value when the antifuse has been programmed and the voltage greater than the threshold voltage is applied to the gate, the second value being one or more orders of magnitude lower than the first value.
19. The method as claimed in claim 15 , wherein the MOSFET includes a source region and a drain region separated from the source region by a conduction channel, the method further comprising detecting an electrical resistance between the source region and the drain region when a voltage greater than a threshold voltage for turning off the conduction channel is applied to the gate, and using the detected resistance to determine whether or not the antifuse has been programmed.
20. The method as claimed in claim 15 , wherein the step of driving the programming current is performed by applying a programming voltage which is the same as a power supply voltage used to operate field effect transistors on a semiconductor chip which embodies the antifuse.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
August 1, 2014
June 16, 2015
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